Since millions of motor vehicles are travelling along roads around the globe day and night, year around, there is constantly an imminent risk of vehicles running off the road for one reason or another. A road departure may result in body injuries and/or damage to the ego vehicle and/or other vehicles involved. In striving to avoid a vehicle leaving the drivable road surface, motor vehicles may be provided with driver assistance systems. These systems may monitor the surroundings of the vehicle, decide whether an imminent road departure is likely to occur, and may further warn and/or intervene with the steering system and/or the brake system of the vehicle in order to prevent the impending or probable road departure. To assess an imminent risk of a vehicle running off the road, information about the vehicle's position in relation to a road boundary of said road, as well as the shape—i.e., the geometry—of the road boundary, may be desired to be determined. To detect and estimate this information, one or more sensors on-board the vehicle may be utilized, such as one or more cameras. For one reason or another, however, the quality of the road boundary detection and/or estimation may be inherently limited, for instance due to insignificant contrast between the drivable surface and the area outside the drivable surface, and/or due to irregularities of the road boundary. Furthermore, darkness, specific road conditions, etc., could worsen the problem. The effect may be noise and/or uncertainties in the information about the vehicle's position and/or orientation in relation to the road in the estimated geometry of the road boundary. These uncertainties may negatively impact the precision in the assessment of the risk of an imminent road departure. Moreover, the possibility to accurately and comfortably provide automatic control of the vehicle for preventing said vehicle from leaving the drivable road surface, may be negatively affected as a consequence of these uncertainties. Accordingly, to provide an approach for preventing a vehicle from running into and/or cross a road boundary, with high availability and satisfying performance, it is desired to enhance the quality of the road boundary information.
EP 2 012 211, for instance, is set out to—among other things—provide an improved surrounding monitoring system, and accordingly discloses a surrounding monitoring system which includes a radar being arranged to detect a road boundary. Since the detected road boundary does not form a continuous line but rather a large set of detected objects forming an uneven interrupted border, EP 2 012 211 suggests to form a continuous line that estimates the road boundary by determining a shape of a shoulder edge thereof, as commonly known in the art. There is further disclosed that a lateral position of the shoulder edge is determined, and subsequently, that an intervention is generated based on a relative lateral position of the vehicle to the shoulder edge. However, although EP 2 012 211 suggests utilizing a radar for improved quality of the road boundary information, and furthermore subsequently supports preventing an impending or probable road departure in an improved manner, there is still room for alternative approaches to obtain enhanced quality of road boundary information.